The present invention is related generally to the field of medical methods and devices. More particularly, the present invention is related to the oral delivery of substances concurrently with the realignment of teeth.
Orthodontic treatments involve repositioning misaligned teeth and improving bite configurations for improved cosmetic appearance and dental function. Repositioning is accomplished by applying gentle controlled forces to the teeth over an extended period of time. Due to the limited space within the oral cavity and extensive movements that some teeth must undergo, the teeth will often be moved throughout a series of intermediate patterns to properly arrange the teeth. For example, molars may be temporarily moved backwards (distalized) to create adequate space for movement of the incisors. Thus, a single patient may experience an average of 25-30 stages or alignment patterns before achieving the final desired configuration.
Recently, it has been found that such repositioning may be accomplished with the use of a series of removable elastic positioning appliances. Such appliances comprise a thin shell of elastic material that generally conforms to a patient's teeth but is slightly out of alignment with an initial or immediately prior tooth configuration. Placement of the elastic positioner over the teeth applies controlled forces in specific locations to gradually move the teeth into the new configuration. Repetition of this process with successive appliances comprising new configurations eventually move the teeth through a series of intermediate configurations or alignment patterns to a final desired configuration. A full description of an exemplary elastic polymeric positioning appliance is described in U.S. Pat. No. 5,975,893, and in published PCT application WO 98/58596 which designates the United States and which is assigned to the assignee of the present application. Both these documents are incorporated by reference for all purposes.
In addition to their ease of use, polymeric positioning appliances are generally transparent and impart substantial force on the teeth, due to stiffness of the appliance. The stiffness of an elastic positioning appliance is a result of the modulus of the thermoformable polymer materials from which it is made. The higher the modulus of the materials, the higher the stiffness of the appliance. When a patient positions such an appliance over a prescribed group of teeth, one or more of the teeth will provide a base or anchor region for holding the positioning appliance in place while the stiffness of the polymeric material will impart a resilient repositioning force against one or a portion of the remaining teeth. By designing the appliance to cover the teeth, a much larger contact surface area is afforded compared to traditional spring retainers and wire-based appliances.
As described, the appliances are only effective in repositioning teeth when the appliance is placed over the patient's teeth. Removal of the appliance for any reason interrupts the treatment plan and lengthens the overall period of treatment. Therefore, removal of the appliance should be minimized for effective and timely treatment. However, a number of dental and periodontal therapies which may be desired or required by the patient may not be effectively utilized while the appliance is in place. Such therapies may be prescribed by a practitioner to improve oral health or they may be requested by the patient for cosmetic purposes.
Oral health concerns often include tooth decay, gingivitis, and periodontitis, to name a few. Tooth decay may be largely prevented or arrested with fluoride treatment. Treatments include toothpastes, gels, rinses and varnishes. Gum disease, such as gingivitis or periodontitis, is caused by bacterial growth associated with dental plaque and calculus deposits. The most common recommendation for preventing such bacterial growth is to mechanically remove the plaque from the tooth surfaces. However, chronic gingivitis and tooth decay have plagued many individuals who in fact comply with good oral hygiene methods and plaque removal. This may be due to a variety of factors including genetic predispositions, illnesses, mouth breathing, and medical treatment programs.
In such cases, bacterial control may be accomplished with the use of antibacterial drugs. A common antibacterial agent shown to be effective in reducing the activity of many common strains of oral flora is chlorhexidine. Chlorhexidine is a cationic biguanide microbicide with a broad spectrum of activity against many forms of bacteria and fungi. Therefore, it has been a popular agent in many studies of gingivitis reversal. Chlorhexidine has traditionally been delivered to the oral environment through the use of rinses, such as Peridex® (Proctor and Gamble). Sustained delivery to the gingiva has also been attempted with the use of chlorhexidine impregnated dental floss and dental appliances, such as trays or mouthguards.
Another frequently prescribed antibacterial agent is tetracycline. Tetracycline is a broad spectrum antibiotic which is effective against virtually all common groups of pathogenic bacteria, both gram positive and negative. Tetracycline may be combined with an antifungal agent, such as amphotericin, to provide activity against fungi. Tetracycline has traditionally been delivered to the oral environment through systemic administration, although localized delivery has been attempted with the insertion of tetracycline-filled hollow fiber devices into periodontal pockets and the use of tetracycline laden dental appliances, such as trays and mouthguards. In addition, a number of other antibacterial drugs are available for dental and periodontal therapy.
Cosmetic treatments often include tooth bleaching or whitening and breath freshening products. Discolorations of enamel and dentin may occur due to aging, consumption of staining substances (coffee, tea, colas, tobacco), trauma, staining due to systemic tetracycline (antibiotic) therapy, excessive fluoride, nerve degeneration and old dental restorations. Bleaching lightens these discolorations for a whiter or brighter appearance. Typically, a bleaching gel is placed in a thin custom-fitted tray that fits over the teeth. The tray is worn at night for usually 10 to 14 days and may require periodic re-bleaching treatments for approximately one or two nights every six months. Breath freshening products are often used by patients to treat halitosis or for enjoyment of the taste. These include a variety of sprays, rinses, mints, gums, or candies, to name a few.
Many of these therapies require access to the teeth and gingival margin which are typically covered by the elastic repositioning appliance when in use. In addition, some of these therapies may best be administered by localized delivery over extended periods of time which would create substantial interruption of the treatment plan. For example, low level delivery of antibiotics by sustained release methods is often desired to treat periodontal disease. Likewise, treatments such as bleaching and whitening may require interruption of the treatment plan for up to two weeks. Removal of the appliance during these periods would lengthen the overall treatment period. In addition, many of these therapies require the usage of specific devices, gels, rinses, applicators and instructions for each administration of therapy. These accessories may be costly, bulky and difficult to use.
Although removal of the appliance should be minimized, it is necessary to remove the appliance during daily oral hygiene routines, such as brushing and flossing of the teeth. Likewise, the appliance may be removed from time to time for participation in athletic activities or for comfort, such as when eating. The ability to temporarily remove such appliances allows the patient to pursue conventional oral hygiene, but teeth which are covered by the appliances a majority of the time may still be at an increased risk of dental and periodontal disease.
It would be desirable to provide improved devices, systems and methods utilizing elastic repositioning appliances which permit and/or enhance concurrent dental and periodontal therapies. Likewise, it would be desirable to provide such devices, systems and methods which would reduce or eliminate the need for additional accessories and/or protocols to apply such therapies. Further, the devices, systems and methods should be economical and easy to use. At least some of these objectives will be met by the designs and methods of the present invention described hereinafter.